The potassium-sparing diuretics are competitive antagonists that either compete with aldosterone for intracellular cytoplasmic receptor sites, or directly block sodium channels (specifically epithelial sodium channels (ENaC) by amiloride ). The former prevents the production of proteins that are normally synthesized in reaction to aldosterone. These mediator proteins are not produced, and so stimulation of sodium-potassium exchange sites in the collection tubule does not occur. This prevents sodium re-absorption and potassium and hydrogen ion secretion. 
Andreoli, . et al. (1997): Cecil Essentials
of Medicine; (4-th ed.)- Company,.
Fauci, . et al. (1998): Harrison’s principles of internal medicine; (14-th ed.)-The McGraw-Hill Companies INC.,.
Shiau, ., Toren, . (2006): The Toronto Notes 2006: Comprehensive Medical References, 26-nd Ed., Canada.
Tierney, . (1997): Pocket guide to the essentials of diagnosis and treatment; (1-th ed.)- Lange medical book, .
Younger-Lewis,C.; Complete home medical guide;Canadian Medical Association (1-st ed.), Dk Publishing Inc.
Encephalopathy, including Posterior Reversible Encephalopathy Syndrome (PRES), has been described both in postmarketing reports and in the literature. Manifestations include impaired consciousness, convulsions, visual disturbances (including blindness), loss of motor function, movement disorders and psychiatric disturbances. In many cases, changes in the white matter have been detected using imaging techniques and pathologic specimens. Predisposing factors such as hypertension, hypomagnesemia, hypocholesterolemia, high-dose corticosteroids, high Cyclosporine blood concentrations, and graft-versus-host disease have been noted in many but not all of the reported cases. The changes in most cases have been reversible upon discontinuation of Cyclosporine, and in some cases improvement was noted after reduction of dose. It appears that patients receiving liver transplant are more susceptible to encephalopathy than those receiving kidney transplant. Another rare manifestation of Cyclosporine-induced neurotoxicity, occurring in transplant patients more frequently than in other indications, is optic disc edema including papilloedema, with possible visual impairment, secondary to benign intracranial hypertension.